This invention relates to airbag devices mounted in a region of the roof frame of a vehicle.
German Offenlegungsschrift No. 22 49 988 discloses an airbag mounted in the roof frame region of a vehicle in which a casing equipped with valves activable by way of an impact sensor to supply gas into the airbag, is interposed between the roof frame of the vehicle and the airbag to be inflated. The casing may be the casing of a gas generator or a gas reservoir. In this arrangement, the airbag and the casing constitute parts of the inner lining of the roof frame which is often in the form of a canopy covering the entire roof in the interior of the vehicle. Activation of the airbag by generation of gas can be effected by way of an impact sensor in the usual manner, for example, pyrotechnically.
This conventional airbag device takes account of the fact that, in an accident, vehicle occupants should be protected from striking the head against the hard roof frame. This is especially applicable to the side regions of the roof frame since conventional restraint systems such as safety belts are largely ineffectual in a side collision. In the above-mentioned prior art, integration of the airbag and the casing with the roof frame lining advantageously ensures that the airbag device will not protrude into the interior of the vehicle in the unactivated condition. A disadvantage, however, is that, in order to achieve a flush surface of the roof frame lining in the region of the airbag device, the hard casing can be covered by only a very flatly collapsed airbag. As a result, in the first place the airbag must be comparatively small, and in the second place this region of the roof frame forms a hard impact surface for the head of the occupant, for example, when getting in or out of the vehicle, in the deactivated condition of the airbag.